Is a hdd sensor needed when replacing a 5400 hdd with a ssd?

I have a 21.5” iMac Late 2015 desktop and am currently upgrading the hdd to ssd. Both HD’s are the same size so it makes it easy to install the ssd. Yet, when I tried installing the hdd sensor, I noticed right away that there is no room for the sensor wire adapter.

I don’t see any guides talking about 2015 21.5” iMacs but I do see guides for the 27” version. That leads me to ask,

1. Does the computer need a hdd sensor for a 21.5” Late 2015 iMac computer and if so how do you install a sensor when there is no space for it?
2. Would I need to buy a hybrid hard drive that has already a sensor built in?

Thanks for the help in advance.

It appears that no sensor is needed. I have done some tests.

My iMac is a late 2015 and had a 1TB HGST HDD 5400rpm. I replaced it with a Samsung 1TB QVO SSD and fans run at normal speeds an average of 1,200 RPM at rest. Other forums that have a late 2015 iMac with a 4K monitor have also had great results with just swapping the drive without the sensor. One reports running his computer for 2+ years without a problem.

I don’t know why iFixit advertises the sensor for the 2015 iMac 21.5” along with the 2015 27” iMac.

My advise for those who have the same type of computer, and run into the same question with not many specific forums on this model of computer, is don’t buy the sensor and save the money if you are upgrading to an ssd. You can avoid buying it and then having to return the item paying shipping and a 25% restocking fee.

Hope this helps.